I have a big bear that isn't running right and was wondering if yall could help me out. It started a couple years ago. It has always never ran right. for the first 5-10 minutes it would never want to idle and then after it was ran for a while it would over idle, reving way to high. Well I dealt with that. Yamaha said to break it in and if it is still doing it after 20 or so hours they would look at it to see what it is. Well I put it up last fall and never pulled it out due to working so much. I finally had a chance to pull it out and it had a hard time starting. Finally it started though and I ran it four about an hour and then parked it and it would never start again.
Well after coming here and doing some reading I went to work on it lastnight and found the hose that goes from the carb to the head/cylinder was blown off the carb, because of the heavy backfires.
So I put it back on and it starts right up. Now when cold with choke full it sounds good, no backfires or anything. But after warming up I lowered the choke slowly and noticed backfiring and it would also die out. The backfires are through the carb.
Also noticed the exhaust pipe was glowing a nice color red. So I'm guess it is running lean, which is causing the not wanting to idle, backfiring, and glwoing pipe. Am I right?
I bought new oil, a new plug and some feul additive to clean the jets that yamaha recommended. I know this isn't going to solve the problem though because it was doing all this within the first hour or two of riding.

So is there some carb adjustments I can due after I put some new fuel, new oil, and new plug in?

I also want to throw in that I have to of these bought at the exact same time and they were always ran at the same time. Now the other bear starts fine, runs fine, no backfires, no glowing pipe.. just runs right. And nothing was done different between the two..

Please help.

 

Sounds like an intake leak to me. The backfiring has been known to cause the carb joints to leak. I have heard of people leaving the park brake on and pulling out till the rev limter kicks in and causing the backfiring and damaging the carb joint. One way I have checked for the intake leak on the carb joint is to spray around the carb joint and where it attaches to the head with starting fluid. If it is leaking the starting fluid will be sucked in to the motor and cause it to rev up. Those carb joints have been known to go bad pretty easily. If it is leaking it would be getting to much air and account for the lean condition. Hope this helps.